#include <bits/stdc++.h>
using namespace std;
string a,b;
int main(){
    cin>>a>>b;
    if(a.find(b)!=a.npos) cout<<b<<" is substring of "<<a<<endl;
    else if(b.find(a)!=b.npos) cout<<a<<" is substring of "<<b<<endl;
    else cout<<"No substring"<<endl;
    return 0;
}

函数，启动！！！

#include <bits/stdc++.h>
using namespace std;
string s1, s2;
int main() {
    cin >> s1 >> s2;
    int strLength = s1.length();
    int subLength = s2.length();
    for (int i = 0; i <= strLength - subLength; i++) {
        bool found = true;
        for (int j = 0; j < subLength; j++) {
            if (s1[i + j] != s2[j]) {
                found = false;
                break;
            }
        }
        if (found) {
            cout << s2 << " is substring of " << s1;
            return 0;
        }
    }
    strLength = s2.length();
    subLength = s1.length();
    for (int i = 0; i <= strLength - subLength; i++) {
        bool found = true;
        for (int j = 0; j < subLength; j++) {
            if (s2[i + j] != s1[j]) {
                found = false;
                break;
            }
        }
        if (found) {
            cout << s1 << " is substring of " << s2;
            return 0;
        }
    }
    cout << "No substring";
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
string s1,s2;
int main(){
    cin>>s1>>s2;
    if(s1.size()<s2.size()){
        swap(s1,s2);
    }
    if(s1.find(s2)==-1){
        cout<<"No substring";
    }else{
        cout<<s2<<" is substring of "<<s1;
    }
    return 0;
}

```
#include<bits/stdc++.h>
using namespace std;
string a,b;
int main()
{
    cin>>a>>b;
    if(a.find(b)!=a.npos)    //如果b是a的子串 
    {
        cout<<b<<" is substring of "<<a<<endl;
    }
    else if(b.find(a)!=b.npos)   //如果a是b的子串 
    {
        cout<<a<<" is substring of "<<b<<endl;
    }
    else      //如果没有子串关系 
    {
        cout<<"No substring"<<endl;
    }
    return 0;
}

#include<bits/stdc++.h> using namespace std; bool StrSubCompare(string s1,string s2){ int lens1=int(s1.size()); int lens2=int(s2.size()); if(lens1>=lens2){ for(int i=0;i<lens1;i++){ if(s2[0]s1[i]){ for(int x=0;x<lens2;x++){ if(s2[x]!=s1[i+x]){ break; } else if(xlens2-1&&s2[x]==s1[i+x]){ return true; } } } } } else{ return false; }

} int main(){ string str1,str2; getline(cin,str1); getline(cin,str2); if(StrSubCompare(str1,str2)==true){ cout<<str2<<" "<<"is substring of "<<str1; } else if(StrSubCompare(str2,str1)==true){ cout<<str1<<" "<<"is substring of "<<str2; } else{ cout<<"No substring"; } return 0; }